Magnetoresistance effect device, and magnetoresistance effect magnetic head

ABSTRACT

A magneto-resistive effect element body  11  and a hard magnetic layer  12  for applying a bias magnetic field are disposed between opposing first and second magnetic shields  21  and  22,  each made of a soft magnetic material. This magneto-resistive effect element body  11  is comprised of a lamination layer structure portion in which there are laminated at least a free layer the magnetization of which is rotated in response to an external magnetic field, a fixed layer, an antiferromagnetic layer for fixing the magnetization of the fixed layer and a spacer layer interposed between the free layer and the fixed layer. Then, the magneto-resistive effect element has a CPP type configuration in which a sense current flows to the magneto-resistive effect element body in the direction intersecting the film plane of the lamination layer film. Further, a detection magnetic field is introduced in the direction extending along the film plane direction of the lamination layer film and a bias magnetic field is applied in substantially the direction intersecting the direction in which the above-mentioned detection magnetic field is introduced and in the direction extending along the film plane. In this configuration, under the condition that the detection magnetic field is not applied to the magneto-resistive effect element, magnetic fields substantially applied to the front end and the rear end of the side in which the detection magnetic field is introduced, to be concrete, magnetic fields determined mainly by an induced magnetic field HI induced by the above-mentioned sense current and a bias magnetic field HB are set to the same directions, particularly, in the free layer, whereby a single magnetic domain is nucleated in the free layer with high stability.

TECHNICAL FIELD

[0001] The present invention relates to a magneto-resistive effectelement and a magnetic head using magneto-resistive head in which anoutput can be stabilized while a sensitivity can be avoided from beingdeteriorated.

BACKGROUND ART

[0002] A magnetic sensor or a magnetic head using a spin-valve typemagneto-resistive effect (hereinafter referred to as an “SV type GMR”)element or a tunnel type magneto-resistive effect (hereinafter referredto as a “TN type MR”) element is able to detect a change of an externalmagnetic field based upon a magnetic resistance change generated by achange of a relative angle between a free layer and a fixed layer whosemagnetization is fixed by an antiferromagnetic layer when themagnetization of the free layer made of a soft magnetic material isrotated in response to the external magnetic field.

[0003] In this case, in order to detect the external magnetic field at ahigh efficiency, by a method such as film deposition, annealing in themagnetic field, a uniaxial magnetic anisotropy is given to the freelayer in the direction perpendicular to the direction in which anexternal magnetic field is introduced. As a consequence, although themagnetization of the free layer tends to orient in the two directionsextending along this magnetic anisotropy (the forward direction or thereverse direction relative to the magnetic field to which the anisotropyis given), which direction of the above two directions the magnetizationof the free layer is oriented without application of the externalmagnetic field is not prescribed. As a result, the above-mentionedmagnetic sensor and the above-mentioned magnetic head cannot detect thechange of the external magnetic field with an excellent reproducibility.

[0004] On the other hand, at the end portion of the free layer in thedirection perpendicular to the aforementioned magnetic anisotropydirection (hereinafter referred to as a “side end portion”) , themagnetization becomes difficult to orient in the magnetic anisotropydirection due to an antimagnetic field so that a magnetic domain occurs,which causes a so-called Barkhausen noise which causes the rotation ofthe magnetization to become discontinuous when the magnetization isrotated in response to the external magnetic field.

[0005] Accordingly, when the bias magnetic field is applied to the freelayer in one direction of the above-mentioned magnetic anisotropydirection in an opposing relation to the side end portion of the freelayer, under the condition that other magnetic field is not applied tothe free layer, the free layer is nucleated as a single magnetic domainby confining its magnetization direction in a constant direction. As aresult, the occurrence of the magnetic domain in the above-mentionedfree end of the free layer can be avoided, the Barkhausen noise can beavoided, and the resistance change of the magneto-resistive effectelement can be reproduced by the detection magnetic field with anexcellent reproducibility and at an excellent stability.

[0006] Although this bias magnetic field needs a magnetic fieldintensity high enough to nucleate the free layer as the signal magneticdomain, when the intensity of the bias magnetic field is too high, arotation angle at which the magnetization of the free layer is rotatedin response to the external magnetic field becomes too small so that thesensitivity of the magneto-resistive effect element is loweredunavoidably. Therefore, the material and film thickness of the hardmagnetic layer are selected in such a manner that the sensitivity of themagneto-resistive effect element becomes appropriate.

[0007] When the magneto-resistive effect element has a so-called CPP(Current Perpendicular to Plane) configuration in which a sense currentflows in the direction perpendicular to the film plane of amagneto-resistive effect element body, i.e., in the directionperpendicular to the film plane of the free layer 1 as shown in FIG. 12,a current magnetic field HI generated in the free layer by this sensecurrent Is is generated so as to circulate along the film plane.

[0008] At that time, at the respective central portions of a front end1F of the free layer 1 and a rear end 1R on the opposite side of thefront end, which is the side into which a detection magnetic field isintroduced, the current magnetic fields become parallel to the directionin which the bias magnetic field HB is applied and also become oppositeto each other.

[0009] Accordingly, as mentioned before, when the bias magnetic field HBis applied to the free layer of the magneto-resistive effect element MR,the current magnetic field HI acts in the direction in which the biasmagnetic field HB is increased in intensity and also acts in thedirection in which the bias magnetic field is decreased in intensity atany one of the center of the front end of the free layer and the centerof the rear end of the free layer.

[0010] Therefore, in order to nucleate the free layer as the singlemagnetic domain, a bias magnetic field having an intensity high enoughto prevent the bias magnetic fields from being canceled out should beapplied to the portion in which the current magnetic field HI acts inthe direction in which the intensity of the bias magnetic field isdecreased.

[0011] However, this bias magnetic field becomes too high in intensityat the portion in which the current magnetic field acts in the directionin which the intensity of the bias magnetic field is increased, so thata sensitivity at this portion is lowered, accordingly, the output of themagneto-resistive effect element is decreased.

DISCLOSURE OF INVENTION

[0012] An object of the present invention is to provide amagneto-resistive effect element which can generate a stable outputwhile making it possible to avoid a sensitivity from being lowered dueto a current magnetic field caused by a sense current as described aboveand is also to provide a magnetic head using magneto-resistive headusing this magneto-resistive effect element as a magnetic sensingportion.

[0013] According to the present invention, the direction of a sensecurrent flowing to the direction intersecting, e.g., perpendicular to afilm plane of a magneto-resistive effect element to which a biasmagnetic field is applied is restricted to a specific direction, wherebya sensitivity partly lowered due to unequal current magnetic fieldsbeing canceled out by a bias magnetic field can be decreased. That is,there can be constructed a magneto-resistive effect element and amagnetic head using magneto-resistive head which are able to generatehigh output with high stability.

[0014] In a magneto-resistive effect element according to the presentinvention, a magneto-resistive effect element body and a hard magneticlayer for applying a bias magnetic field to the magneto-resistive effectelement body are disposed between opposing first and second magneticshields, each of which is made of a soft magnetic material.

[0015] The magneto-resistive effect body is comprised of a laminationlayer structure portion in which there are laminated at least a freelayer the magnetization of which is rotated in response to an externalmagnetic field, a fixed layer, an antiferromagnetic layer for fixing themagnetization of this fixed layer and a spacer layer interposed betweenthe free layer and the fixed layer.

[0016] Then, the magneto-resistive effect element has a CPP typeconfiguration in which a sense current flows to the magneto-resistiveeffect element body in the direction crossing the film plane of itslamination layer film. Moreover, a detection magnetic field isintroduced in the direction extending along the film plane direction ofthe lamination layer film, and a bias magnetic field is applied tosubstantially the direction which intersects the direction in which theabove-mentioned detection magnetic field is introduced and in thedirection extending along the film plane of the lamination layer film.

[0017] According to the present invention, in this configuration,particularly in the free layer, under the condition that the detectionmagnetic field is not applied to the magneto-resistive effect element,magnetic fields substantially applied to this free layer at the frontend and the rear end of the side into which this detection magneticfield is introduced, to be concrete, magnetic fields determined mainlyby an induced magnetic field (hereinafter referred to as a “currentmagnetic field HI”) generated by the above-mentioned sense current and abias magnetic field HB are set to the same direction.

[0018] Further, in the magnetic head using magneto-resistive headaccording to the present invention, its magnetic sensing portion iscomprised of the above-mentioned magneto-resistive effect elementaccording to the present invention.

[0019] As described above, according to the present invention, themagnetic head using magneto-resistive head has the magnetic shield typeconfiguration in which the magneto-resistive effect element is disposedbetween the first and second magnetic shields and has also the CPP typeconfiguration. Under the condition that the detection magnetic field isnot applied to the magneto-resistive effect element, directions HF andHR of magnetic fields applied to this free layer are set to the samedirection at the front end and the rear end of the free layer, in actualpractice, at the central portions of the front end and the rear end,whereby an occurrence of a magnetic domain can be avoided insubstantially the whole region of the side end portion of the freelayer. As a result, there can be constructed the magneto-resistiveeffect element and the magnetic head using magneto-resistive head inwhich a Barkhausen noise can effectively be improved, accordingly, themagneto-resistive effect element and the magnetic head usingmagneto-resistive head which are stable and excellent inreproducibility.

[0020] Then, in this configuration in which |HF|>|HR| is fundamentallysatisfied, i.e., in the configuration in which a magnetic field in thedirection perpendicular to the detection magnetic field is increased inintensity in the front portion in which an amount of detection magneticflux is large, the magneto-resistive effect element and the magnetichead using magneto-resistive head can be made stable. On the contrary,in the configuration in which |HF|<|HR| is satisfied, themagneto-resistive effect element and the magnetic head usingmagneto-resistive head can be increased in sensitivity.

[0021] However, as will be described later on, for example, with thestructures in which the magneto-resistive effect element and themagnetic head using magneto-resistive head include magnetic flux guides,under the condition in which the magnetic fields HF and HR are selectedso as to orient in the same direction, the setting of a relationshipbetween the magnetic fields HF and HR and a relationship between thesensitivity and the stability can be selected arbitrarily.

BRIEF DESCRIPTION OF DRAWINGS

[0022]FIG. 1 is a schematic perspective view showing a magneto-resistiveeffect element and a magnetic head according to an embodiment of thepresent invention.

[0023]FIG. 2 is a schematic perspective view showing a magneto-resistiveeffect element and a magnetic head according to another embodiment ofthe present invention.

[0024]FIG. 3 is a schematic cross-sectional view showing amagneto-resistive effect element body according to an embodiment of thepresent invention.

[0025]FIG. 4 is a schematic cross-sectional view showing amagneto-resistive effect element body according to another embodiment ofthe present invention.

[0026]FIG. 5 is a schematic cross-sectional view showing amagneto-resistive effect element and a magnetic head according to anembodiment of the present invention.

[0027]FIG. 6 is a schematic cross-sectional view showing amagneto-resistive effect element and a magnetic head according toanother embodiment of the present invention.

[0028]FIG. 7 is a diagram to which reference will be made in explainingthe present invention and which shows an induced current induced by asense current flowing through a free layer.

[0029]FIG. 8 is a diagram to which reference will be made in explainingthe present invention and which shows a coordinate system.

[0030]FIG. 10 is a diagram showing distributions of magnetic fieldsgenerated in the depth direction of the magneto-resistive effectelement.

[0031]FIG. 11 is a schematic perspective view showing an example of arecording and reproducing magnetic head using a magnetic head accordingto the present invention.

[0032]FIG. 12 is a diagram showing a sense current and a currentmagnetic field.

BEST MODE FOR CARRYING OUT THE INVENTION

[0033] A magneto-resistive effect (MR) element according to the presentinvention and an MR type magnetic head using this inventivemagneto-resistive effect element will be described.

[0034]FIGS. 1 and 2 show schematic perspectives of an MR element 10 andan MR type magnetic head 100 using this inventive magneto-resistiveelement according to the present invention, respectively.

[0035] The MR element 10 includes an MR element body 11 and a hardmagnetic layer 12 for applying a bias magnetic field to thismagneto-resistive effect element body disposed between first and secondmagnetic shields opposing to each other, e.g., first and secondelectrode and magnetic shields 21 and 22 serving as electrodes as welland each of which is made of a soft magnetic material having aconductivity.

[0036] The example shown in FIG. 1 shows the case in which the MRelement body 11 is disposed in a facing relation to a surface into whicha detection magnetic field is introduced, i.e., a forward surface 13.FIG. 2 shows the case in which the MR element body 11 is disposed at aposition retreated from this forward surface 13 in the depth directionsuch that a detection magnetic field introduced from this forwardsurface 13, i.e., in a magnetic head, a signal magnetic field from arecording portion of a magnetic recording medium (not shown) isintroduced into the MR element body 11 by a magnetic flux guide layer14.

[0037] This magnetic flux guide layer 14 can be formed as a free layerand magnetic flux guide layer or this magnetic flux guide layer can bebonded to the free layer.

[0038] In FIGS. 1 and 2, it is to be desired that the magnetic fluxguide layers 14 should be disposed behind the respective MR elementbodies 11 or the magnetic flux guide layers should be extended from therear portions of the respective magneto-resistive effect element bodies.

[0039] A nonmagnetic insulating layer 15 made of Al₂O₃, for example, isburied between the first and second electrode and magnetic shields 21and 22.

[0040] [First Embodiment]

[0041] In this embodiment, the magneto-resistive effect element has asingle SV type GMR configuration. In this case, as FIG. 3 shows aschematic cross-sectional view thereof, its MR element body 11 has alamination layer structure comprising at least a free layer 1 themagnetization of which is rotated in response to a detection magneticfield, a fixed layer 2, an antiferromagnetic layer 3 for fixing amagnetization of this fixed layer 2 and a spacer layer 4 interposedbetween the free layer 1 and the fixed layer 2. In the illustratedexample, this magneto-resistive effect element has a configuration inwhich an underlayer 5 is formed on the lower surface of theantiferromagnetic layer 3 and in which a magnetic flux guide layer 14, amagnetic gap layer 6 and a capping layer 7 are formed on the free layer1.

[0042] As shown in FIG. 1 or 2, this MR element body 11 is disposedbetween the first and second electrode and magnetic shields 21 and 22 insuch a manner that the plane directions of the respective layers of theMR element body 10 become parallel to these shields 21 and 22.

[0043] In this case, on a substrate 16 made of an AlTiC (AlTiC) layerhaving a thickness of 100 μm, for example, there is formed the firstelectrode and magnetic shield 21 made of an NiFe layer having thicknessof 2 μm by plating, for example, on which the underlayer 5 shown in FIG.3 is deposited by sputtering. Subsequently, on this underlayer, thereare deposited the antiferromagnetic layer 3, the fixed layer 2, thespacer layer 4 and the free layer 1 by sputtering, in that order,thereby resulting in a lamination layer film of the antiferromagneticlayer 3, the fixed layer 2, the spacer layer 4 and the free layer 1being formed. Then, a first stripe portion is formed by patterning thislamination layer film like a stripe extending along the track widthdirection, for example.

[0044] An insulating layer 15 made of SiO₂ or Al₂O₃, for example, isformed so as to bury this first stripe portion, and a flat surface towhich the free layer 1 is faced is formed. An NiFe layer, for example,comprising the magnetic flux guide layer 14, for example, is formed onthis flat surface and a second stripe portion is formed like a stripeextending in the thickness direction including this layer and theabove-mentioned stripe portion below this layer, i.e., in the directionperpendicular to the aforementioned stripe direction by patterning.

[0045] In this manner, the above-mentioned lamination layer film is leftin only the portion at which the first and second stripe portions crosseach other, whereby the MR element body 11 like a square one side ofwhich is 100 nm, for example, and which is based upon the laminationlayer structure portion of the antiferromagnetic layer 3, the fixedlayer 2, the spacer layer 4 and the free layer 1 is constructed.

[0046] Then, there is formed the stripe-like magnetic flux guide layer14 under which there are laminated the insulating layer 15 made of SiO₂or Al₂O₃, for example, the hard magnetic layer 12 and the similarinsulating layer 15 so as to bury the second stripe portion includingthe MR element body 11 based upon the above-mentioned lamination layerstructure portion, e.g., so as to be deposited on both side surfaces ofthe second stripe portion, for example. Then, the insulating layer 15and the hard magnetic layer 12 are selectively removed from the secondstripe portion by a lift-off method, for example, whereby the surfacecan be made flat. As shown in FIG. 3, on this flat surface, there areformed the gap layer 6 and the capping layer 7 on which there is furtherformed the second electrode and magnetic shield 22 formed of the NiFeplating layer having a thickness of 2 μm, for example.

[0047] In the MR element body 11 formed between the first and secondelectrode and magnetic shields 21 and 22 as described above, thethickness of the gap layer 7 shown in FIG. 3, for example, is selectedin such a manner that the free layer 1 and the magnetic flux guide layer14 may be located at substantially the center between the first andsecond electrode and magnetic shields 21 and 22.

[0048] Then, the hard magnetic layers 12 are disposed at the positionsopposing to respective side end portions of this free layer 1.

[0049] The free layer 1 and the fixed layer 2 can be each formed of aCoFe film having a thickness of 5 nm, for example.

[0050] The free layer 1 is given a uniaxial anisotropy of an anisotropicmagnetic field of 5 [Oe] in the film plane direction shown by an arrow ain FIG. 1, for example, by film deposition in the magnetic fieldgenerated by a magnetic field of 500 [Oe], for example, and by vacuumannealing for 1 hour in the magnetic field generated by a magnetic fieldof 1000 [Oe] at 200° C.

[0051] The spacer layer 4 interposed between these free layer 1 andfixed layer 2 can be formed of a conductive layer, for example, a Culayer having a thickness of 3 nm, for example.

[0052] Moreover, the antiferromagnetic layer 3 can be formed of a PtMnfilm, for example, having a thickness of 34.5 nm, for example.

[0053] The hard magnetic layers 12 are magnetized as shown by arrows bin one direction which is the same direction as that of the anisotropicmagnetic field of the free layer as shown in FIGS. 1 and 2.

[0054] When the hard magnetic layers 12 are buried by the insulatinglayer 15 and thereby electrically separated from the MR element body 11,they can be each formed of a conductive CoCrPt film having a thicknessof 40 nm, for example. The residual magnetization of the hard magneticlayers 12 formed of the CoCrPt film is 670 [emu/cm³]. Moreover, when thehard magnetic layers 12 are not electrically separated from the MRelement body 11, these hard magnetic layers can be made of a Co—Fe₂O₃film having a high resistance.

[0055] The underlayer 5 and the capping layer 7 can be each formed of aTa film having a thickness of 3 nm, respectively.

[0056] The magnetic gap layer 6 can be formed of a nonmagnetic film,e.g., Cu film having a thickness of 34.5 nm.

[0057] In this configuration, the magnetic flux guide layer 14 can alsoserve as the free layer 1 as well.

[0058] Then, the forward surface 13 can be formed by polishing and theMR element body 11 can be directly faced to the forward surface, wherebythe magnetic flux guide layer 14 can be extended from themagneto-resistive effect element body to the rearward as shown inFIG. 1. Alternatively, as shown in FIG. 2, the front end of the magneticflux guide layer 14 may be faced to the forward surface 13 and the MRelement body 11 may be located at the position retreated from the frontend of the magnetic flux guide layer in the depth direction.

[0059] In the magnetic head 100 using this MR element 10, the forwardsurface 13 comprises a surface by which the magnetic head 100 is broughtin contact with a magnetic recording medium or the magnetic head isopposed to the magnetic recording medium.

[0060] In a flying type magnetic head, for example, this forward surfaceserves as a so-called ABS surface (Air Bearing Surface) by which themagnetic head can fly over a recording medium surface with a requiredspace between them due to an air flow generated by a relative movementof a magnetic recording medium, e.g., a magnetic disk and a magnetichead.

[0061] Then, according to the present invention, this configurationserves as a CPP type configuration in which a sense current is flowingbetween the first and second electrode and magnetic shields 21 and 22,i.e., the MR element body 11 in the direction intersecting the filmplane of the lamination layer film.

[0062] Further, the detection magnetic field may be introduced along thefilm plane direction of the lamination layer film. At the same time, thebias magnetic field HB generated by the hard magnetic layer 12 may beapplied not only in the direction intersecting substantially thedirection in which the above-mentioned detection magnetic field isintroduced but also in the direction along the film plane, i.e., in thedirection along the anisotropic magnetic field direction, shown by thearrow a, of the free layer, e.g., in the direction shown by the arrow b.

[0063] Then, according to the present invention, in the above-mentionedconfiguration, for example, in particular, in the free layer, as will bedescribed later on in detail, under the condition that the detectionmagnetic field is not applied to the magneto-resistive effect element,magnetic fields which are substantially applied to the front end and therear end of the side into which the detection magnetic field isintroduced, to be concrete, magnetic fields determined by mainly theinduced magnetic fields generated by the above-mentioned sense current,i.e., magnetic fields determined by the current magnetic field HI andthe above-mentioned bias magnetic field HB are set to the samedirection.

[0064] [Second Embodiment]

[0065] In this embodiment, as FIGS. 5 and 6 show schematic longitudinalcross-sectional views of FIGS. 1 and 2, the magneto-resistive effectelement has a so-called dual SV type GMR element 10 in which MR elementbodies 11A and 11B having a pair of SV type GMR configurations aresymmetrically disposed across a common magnetic flux guide layer or afree layer and magnetic flux guide layer 14.

[0066] Particularly, in this case, as FIG. 4 shows a schematiccross-sectional view of its MR element body 11, spacers 4A and 4B, fixedlayers 2A and 2B and antiferromagnetic layers 3A and 3B comprising therespective element bodies 11A and 11B are disposed at both surfaces ofthe free layer and magnetic flux guide layer 14 which serves also as thefree layers 1A and 1B as well.

[0067] In FIG. 4, elements and parts identical to those of FIG. 3 aredenoted by identical reference numerals and therefore an overlappingexplanation will be omitted.

[0068] The free layer and magnetic flux guide layer 14, the spacerlayers 4A and 4B, the fixed layers 2A and 2B and the antiferromagneticlayers 3A and 3B may have configurations similar to those of the freelayer 1 or the magnetic flux guide layer 14, the spacer layer 4, thefixed layer 2 and the antiferromagnetic layer 3 in the aforementionedfirst embodiment, for example.

[0069] Also in this embodiment, in the magnetic head 100 using this MRelement 10, its forward surface 13 comprises a surface by which themagnetic head comes in contact with and is opposed to a magneticrecording medium. In a flying type magnetic head, for example, thisforward surface serves as what might be called an “ABS surface” (AirBearing Surface) by which the magnetic head can fly over a recordingmedium surface by a required space owing to an air flow produced when amagnetic recording medium, e.g., a magnetic disk and the magnetic headare moved in a relative relationship between them.

[0070] Further, also in this case, the magneto-resistive effect elementhas the CPP type configuration in which the sense current flows betweenthe first and second electrode and magnetic shields 21 and 22, i.e., theMR element body 11 in the direction crossing the film plane of itslamination layer film.

[0071] Furthermore, the detection magnetic field is introduced into thedirection extending along the film plane direction of the laminationlayer film. At the same time, the bias magnetic field HB caused by thehard magnetic layer 12 is applied to the direction crossing thedirection in which the above-mentioned detection magnetic field isintroduced and in the direction extending along the film plane, i.e., inthe direction extending along the anisotropic magnetic field directionshown by the arrow a in the free layer, e.g., one direction shown by thearrow b.

[0072] Then, according to the present invention, in such configuration,for example, particularly in the free layer, under the condition thatthe detection magnetic field is not applied to the magneto-resistiveeffect element, as will be described later on, magnetic fieldssubstantially applied to this free layer at the front end and the rearend of the side into which this detection magnetic field is introduced,to be concrete, magnetic fields determined by mainly the inducedmagnetic field generated by the above-mentioned sense current, i.e., thecurrent magnetic field HI and the above-mentioned bias magnetic field HBare set to the same direction, particularly, in the free layer.

[0073] [Third Embodiment]

[0074] In this embodiment, the magneto-resistive effect element has a TNtype MR configuration. In this embodiment, the magneto-resistive effectelement has a similar configuration to that of the first embodiment andis different only in that the spacer layer in the aforementioned firstembodiment is formed of an Al₂O₃ layer which is what might be called atunnel barrier layer formed by treating an Al layer having a thicknessof 0.6 nm by anodic oxidation.

[0075] [Fourth Embodiment]

[0076] In this embodiment, the magneto-resistive effect element has a TNtype MR configuration. In this embodiment, the magneto-resistive effectelement has a similar configuration to that of the above-mentionedsecond embodiment and is different only in that the spacer layer in theaforementioned second embodiment is formed of an Al₂O₃ layer which iswhat might be called a tunnel barrier layer formed by treating an Allayer having a thickness of 0.6 nm by anodic oxidation.

[0077] As mentioned before, according to the MR element 10 or themagnetic head 100 of the present invention, in the free layer, under thecondition that the detection magnetic field is not applied to themagneto-resistive effect element, as will be described later on indetail, magnetic fields substantially applied to the free layer at thefront end and the rear end of the side in which this detection magneticfield is introduced, to be concrete, magnetic fields determined bymainly the induced magnetic field generated by the above-mentioned sensecurrent, i.e., the current magnetic field HI and the above-mentionedbias magnetic field HB are set to the same direction, particularly, inthe free layer. This will be described.

[0078]FIG. 7 shows the bias magnetic field direction HB of the biasmagnetic field applied to the free layer 1 and a current magnetic field(shown by an arrow c) within the film plane as is obtained by anumerical calculation based upon a finite element method. FIG. 7 showsthe state in which the sense current Is flows to the upper directionperpendicular to the sheet of the drawing.

[0079] In the present invention, at respective central portions of afront end 1F and a rear end 1R of this free layer 1, the directions ofthe magnetic fields applied to this free layer 1 are set to thedirection extending along the anisotropic magnetic field of the freelayer 1 and the same direction.

[0080] This will be described.

[0081] When a magnetic field component Hx in a direction x perpendicularto an external magnetic field Hsig of the current magnetic field HI on acenter line parallel to the external magnetic field (detection magneticfield) Hsig of the free layer is calculated from the Bio-Savart Law andthe following equation (1) obtained from a coordinate system defined asshown in FIG. 8, this component is calculated as shown by a dashed linein FIG. 9A. In this case, in the magnetic field component Hx, a polarityof the same direction as that of the bias magnetic field HB is set to apositive polarity. $\begin{matrix}{{H_{x}\left( {x,y,{z = 0}} \right)} = {\frac{I_{s}}{10}{\int_{x^{\prime} = 0}^{x^{\prime} = L}{\int_{y^{\prime} = 0}^{y^{\prime} = L}{\int_{z^{\prime} = h}^{z^{\prime} = h}{\frac{y^{\prime} - y}{\left( {z^{\prime 2} - R^{2}} \right)^{3/2}}{z^{\prime}}{y^{\prime}}{x^{\prime}}}}}}}} & \left( {{Equation}\quad 1} \right)\end{matrix}$

[0082] wherein H_(x): x component(Oe) of current magnetic field

[0083] x,y,z : position in the device (cm)

[0084] R={square root}{square root over ((x-x′)²+(y-y′)²)} I_(s): sensecurrent (A)

[0085] In this case, since the current magnetic field component Hx inthe tip, i.e., the front end 1F is −120 [Oe] and becomes larger than themagnetic anisotropic magnetic field, it is to be understood that thefree layer 1 cannot be nucleated as a single magnetic domain withoutapplication of the bias magnetic field HB. Then, in this case, at thelowest, there is required the intensity of the bias magnetic field suchthat the direction of the synthesized magnetic field of the currentmagnetic field component Hx and the bias magnetic field HB become thesame direction at the center line A in which the magnetic fieldcomponent Hx becomes largest.

[0086] Therefore, characteristics of the material and the film thicknessof the hard magnetic layer 12 are adjusted in such a manner that thebias magnetic field applied onto the center line A may exceed 120 [Oe],e.g., may reach 130 [Oe]. As a consequence, the synthesized magneticfield on the center line A is obtained as shown by a solid curved linein FIG. 9A.

[0087] With this configuration, the synthesized magnetic field of thecurrent magnetic field HI and the bias magnetic field HB are oriented inthe same direction in the direction crossing, e.g., perpendicular to thedirection of the external magnetic field (detection magnetic field) Hsignot only on the center line A but also in the whole region of the freelayer 1 with the result that the free layer 1 can be nucleated as asingle magnetic domain in its whole region.

[0088] However, at that time, a synthesized magnetic field as large as270 [Oe] is applied to the rear end 1R of the free layer 1. Hence, it isto be considered that a sensitivity is lowered at the rear end of thefree layer 1.

[0089] However, in the above-mentioned configuration of the presentinvention, since the magneto-resistive effect element has theconfiguration in which the MR element 10 is sandwiched between the firstand the second magnetic shields 21 and 22, i.e., the so-called shieldtype configuration, a region in which the detection magnetic field isintroduced i.e., a detection space is limited so that a resolution ofthe magneto-resistive effect element can be increased. According to theshield type configuration, when magnetic flux of the detection magneticfield is propagated from the front end (tip) of the free layer to therear end, it is customary that a magnetic field is attenuated due to theleakage of magnetic flux leaked to the shields 21 and 22 adjacent to themagneto-resistive effect element body.

[0090] It is well known that a degree to which this magnetic field isattenuated by the leakage of the magnetic flux can be expressed as inthe following equation (3) by using a magnetic flux penetrationcharacteristic length λ defined in the following equation (2).$\begin{matrix}{\lambda = \sqrt{\frac{\mu \quad {gt}}{2}}} & \left( {{Equation}\quad 2} \right)\end{matrix}$

[0091] μ: magnetic permeability of the free layer

[0092] g: distance from the free layer to the shield

[0093] t: layer thickness of the free layer $\begin{matrix}{{\Phi (y)} = {{\Phi (0)}\frac{\sinh \left( {\left( {D - y} \right)/\lambda} \right)}{\sinh \left( {D/\lambda} \right)}}} & \left( {{Equation}\quad 3} \right)\end{matrix}$

[0094] Φ(y): magnetic flux at the distance y from the top end of thefree layer, i.e., the magnetic flux guide

[0095] D: distance from the front end to the rear end of free layer,i.e., the magnetic flux guide

[0096] λ: flux penetration characteristic length shown by the equation2.

[0097] In the above-mentioned configuration of the present invention,the attenuation degree of the magnetic field is calculated as shown inFIG. 9C. From FIG. 9C, it is to be understood that the magnetic flux isthoroughly attenuated at the rear end portion of the free layer 1. Thatis, it is to be understood that the contribution of the attenuation ofthe magnetic flux to the magnetic resistance change in the rear endportion 1R is extremely small compared with the front end 1F. Therefore,as mentioned before, even when the magnetic field of the x directioncomponent is remarkably increased at the rear end portion of the freelayer 1, it is possible to avoid a trouble caused by such increasedmagnetic field.

[0098] On the other hand, if the sense current flows in the directionopposite to the direction in which the sense current Is flows as shownin FIG. 7, then when the similar component Hx in the direction xperpendicular to the external magnetic field Hsig at the center line Ais calculated, such component is calculated as shown by a dashed line inFIG. 9B. Further, when a bias magnetic field necessary for nucleatingthe free layer 1 as the single magnetic domain is applied to the freelayer, the above component is calculated as shown by a solid line inFIG. 9B.

[0099] Then, in this case, although a sensitivity can be increased nearthe rear end portion 1R of the free layer 1, a benefit of such increasedsensitivity can hardly be obtained due to the above-mentioned magneticflux attenuation effect.

[0100] That is, according to the present invention, by selecting arelationship between the direction and intensity of the bias magneticfield HB and a relationship between the conducting direction andconducting current amount of the sense current, i.e., the direction andintensity of the current magnetic field HI, the change of the magneticfield of the detection magnetic field Hsig can be detected moreefficiently, i.e., a high reproduced output can be realized.

[0101] This will further be described with reference to FIG. 10. In thissheet of drawing, there are illustrated magnetic field distributionsobtained in a dual type MR element in which a pair of MR element bodies11A and 11B are disposed across the free layer 1 and magnetic flux guidelayer 14. In FIG. 10, a curve 31 shows a magnetic field distribution ofthe current magnetic field HI obtained under the condition that only thesense current flows to the free layer, i.e., under the condition thatthe bias magnetic field is not applied to the free layer. A curve 32shows a magnetic field distribution obtained when the bias magneticfield HB of the same direction as that of the magnetic field HI in thefront end 1F of the free layer 1 is applied to this current magneticfield HI. Although magnetic fields HF and HR of total sums (hereinafterreferred to as “total sum magnetic fields”) of the current magneticfields HI and the bias magnetic fields HB of the front end side and therear end side are set to the same direction, the intensities of thesecurrent magnetic fields are assumed to be |HF|>|HR|.

[0102] A curve 33 shows a magnetic field distribution obtained when thebias magnetic field HB in the opposite direction to that of the curve 32and |HF|<|HR| is satisfied although the magnetic field HR on the rearend side and the magnetic field HF on the rear end side are set to thesame direction.

[0103] As mentioned before, in order to increase the sensitivity of theelement, the state of the curve 33 in which |HF|<|HR| is satisfiedshould be preferable. However, in the case of the magneto-resistiveeffect element including the magnetic flux guide layer 14 shown in FIG.10, the current magnetic field HI and the bias magnetic field HB appliedto the magnetic flux guide layer 14 affect the reproduced output of theelement. That is, in the state shown by the curve 33, |HF| is small sothat the sensitivity can be increased at the front end in which themagnetic flux efficiency is high. However, since |HR| is large, amagnetic flux extracting effect at the portions behind the elementbodies 11A and 11B of the magnetic flux guide layer 14 becomes small sothat magnetic flux directly leaked from the element bodies 11A and 11Bto the magnetic shields is increased unavoidably.

[0104] On the other hand, in the state shown by the curve 32, since |HF|is large, although the sensitivity is lowered at the front end in whichthe magnetic flux efficiency is high, |HR| is small with the result thatthe magnetic flux extracting effect at the portions behind the elementbodies 11A and 11B of the magnetic flux guide layer 14 is increased.Thus, it is possible to decrease the magnetic flux directly leaked fromthe element bodies 11A and 11B to the magnetic shields.

[0105] That is, we cannot always say which reproduced output is higherin intensity between the state shown by the curve 33 in which thesensitivity of the element is small but the magnetic flux leakage islarge and the state shown by the curve 32 in which the sensitivity ofthe element is small but the magnetic flux leakage is small, and thereproduced output is changed depending upon the structure and dimensionof the element. Accordingly, which configuration to select should bedetermined in accordance with the structure and dimension of theelement.

[0106] Further, when a difference between the reproduced output in thestate shown by the curve 32 and in the state shown by the curve 33 isnot so large, it should be preferable to select the configuration whichcan present the state of the curve 32 in which the sum of the currentmagnetic field HI and the bias magnetic field HB is large at the frontend in which the contribution to the reproduced output is large and thestability is excellent.

[0107] That is, according to the configuration of the present invention,since the total magnetic fields are set to the same direction over thewhole region of the front and the rear of the free layer 1, the freelayer is nucleated as a single magnetic domain over the whole region,thereby improving the Barkhausen noise effectively. In addition, byincreasing the magnitude of the total magnetic field at the front end orthe rear end of the free layer, there can be achieved the effect thatthe sensitivity can be increased much more or the stability can beimproved.

[0108] Further, while the magnetic head 100 according to the presentinvention can be used as a head for detecting a signal from a magneticrecording medium, i.e., a reproducing head, when the magnetic headaccording to the present invention comprises a recording and reproducinghead, an induction type thin-film recording head is disposed on thesecond magnetic shield and electrode 22, for example, shown in FIG. 1 or2, for example, and thereby can be integrally formed with the aboverecording head as one body.

[0109]FIG. 11 shows a schematic perspective view of such example. Inthis example, the magnetic head according to the present invention canbe constructed as a magnetic recording and reproducing head bylaminating an electromagnetic induction type thin-film magneticrecording head 130, for example, on the inventive magnetic head 100using the MR element according to the present invention as a magneticsensing portion.

[0110] Then, at the portion which faces the forward surface 13, there isformed a nonmagnetic layer 131 made of an SiO₂ layer and the like, forexample, comprising the magnetic gap of the recording head 130.

[0111] Then, a coil 132, which is formed by patterning a conductivelayer, for example, is formed on the rear portion. An insulating layeris deposited on the coil 132, and a through-hole 133 is bored throughthe insulating layer and the nonmagnetic layer 131 at its centralportion of this coil 132 to thereby expose the second shield andelectrode 2.

[0112] On the other hand, the front end of the forward surface 3 isopposed to the nonmagnetic layer 131 and, on the nonmagnetic layer 131,there is formed a magnetic core layer 134 which is brought in contactwith the second shield and electrode layer 22 exposed through thethrough-hole 133 across the portion in which the coil 132 is formed.

[0113] In this manner, there is constructed the electromagneticinduction type thin-film recording head 130 in which a magnetic gap gprescribed by the thickness of the nonmagnetic layer 131 is formedbetween the front end of the magnetic core layer 134 and the secondshield and electrode layer 2.

[0114] On this magnetic head 130, there is formed a protecting layer 135comprised of an insulating layer as shown by a dot-and-dash line.

[0115] As described above, there can be constructed the recording andreproducing magnetic head 130 in which the magneto-resistive effect typereproducing magnetic head 100 according to the present invention and thethin-film type recording head 130 are laminated and thereby integratedas one body.

[0116] The present invention is not limited to the above-mentionedexamples and can be modified as various types of magneto-resistiveeffect elements such as a so-called synthetic type, a single or dualtype in which a fixed layer, for example, is formed as a laminationlayer ferri-structure. Further, materials and thicknesses of respectivelayers are not limited to the above-mentioned examples and can bevariously modified.

[0117] As described above, according to the configuration of the presentinvention, the magneto-resistive effect element has the magnetic shieldtype configuration in which the magneto-resistive effect element isdisposed between the first and second magnetic shields and has also theCPP type configuration. Under the condition that the detection magneticfield is not applied to this configuration, since the directions of themagnetic fields substantially applied to the free layer, i.e., thedirections of the total magnetic fields are set to the same direction atthe front end and the rear end, in actual practice, over the front endand the rear end, the free layer can be nucleated as the single magneticdomain over the whole region of the side end portion of the free layer.As a result, the Barkhausen noise can be improved effectively.

[0118] Further, since the respective total magnetic fields |HF| and |HR|are selected so as to satisfy |HF|<|HR| or |HF|>|HR|, the stability orsensitivity of the magneto-resistive effect element can be improved muchmore. Therefore, there can be constructed the magneto-resistive effectelement which is excellent in reproducibility and the magnetic headwhich uses this magneto-resistive effect element as the magnetic sensingportion. LIST OF REFERENCE NUMERALS AND ITEMS Reference Numerals Items 1 the free layer  1F the front end  1R the rear end  2, 2A, 2B thefixed layers  3, 3A, 3B the antiferromagnetic layers  4, 4A, 4B thespacer layers  5 the underlayer  6 the magnetic gap layer  7 the cappinglayer  10 the MR element  11 the MR element body  12 the hard magneticlayer  13 the forward surface  14 the magnetic flux guide layer  15 theinsulating layer  16 the substrate 100 the MR type magnetic head 130 themagnetic induction type thin-film magnetic head 131 the nonmagneticlayer 132 the coil 133 the through-hole 134 the magnetic core layer 135the protecting layer

1. A magneto-resistive effect element characterized in that amagneto-resistive effect element body having a lamination layer filmcomprising at least a free layer the magnetization of which is rotatedin response to an external magnetic field, a fixed layer, anantiferromagnetic layer and a spacer layer interposed between said freelayer and said fixed layer and a hard magnetic layer for applying a biasmagnetic field to said magneto-resistive effect element body aredisposed between opposing first and second magnetic shields, each madeof a soft magnetic material, a sense current flows to saidmagneto-resistive effect element body in the direction intersecting thefilm plane direction of said lamination layer film and a detectionmagnetic field is introduced in the direction extending along the filmplane direction of said lamination layer film, said bias magnetic fieldis applied in substantially the direction intersecting the direction inwhich said detection magnetic field is introduced and in the directionextending along said film plane direction and directions of magneticfields substantially applied to the front end and the read end of theside into which said detection magnetic field is introduced are set tothe same direction in said free layer under the condition that saiddetection magnetic field is not applied to said magneto-resistive effectelement.
 2. A magneto-resistive effect element according to claim 1,characterized in that said magnetic fields substantially applied to thefront end and the rear end of the side into which said detectionmagnetic field is introduced in said free layer under the condition thatsaid detection magnetic field is not applied to said magneto-resistiveeffect element are increased in said rear end side.
 3. Amagneto-resistive effect element according to claim 1, characterized inthat said magnetic fields substantially applied to the front end and therear end of the side in which said detection magnetic field isintroduced in said free layer under the condition that said detectionmagnetic field is not applied are increased in said front end side.
 4. Amagneto-resistive effect element according to claim 1, 2 or 3,characterized in that said magneto-resistive effect element body has aspin-valve type configuration in which said spacer layer is comprised ofa nonmagnetic conductive layer.
 5. A magneto-resistive effect elementaccording to claim 1, 2 or 3, characterized in that saidmagneto-resistive effect element body has a tunnel type configuration inwhich said spacer layer is comprised of a tunnel barrier layer.
 6. Amagnetic head using magneto-resistive head characterized in that amagnetic sensing portion of a magnetic head using magneto-resistive headis comprised of a magneto-resistive effect element, saidmagneto-resistive effect element being characterized in that amagneto-resistive effect element body having a lamination layer filmcomprising at least a free layer the magnetization of which is rotatedin response to an external magnetic field, a fixed layer, anantiferromagnetic layer for fixing the magnetization of said fixed layerand a spacer layer interposed between said free layer and said fixedlayer and a hard magnetic layer for applying a bias magnetic field tosaid magneto-resistive effect element body are disposed between opposingfirst and second magnetic shields, each made of a soft magneticmaterial, a sense current flows to said magneto-resistive effect elementbody in the direction intersecting a film plane of said lamination layerfilm and a detection magnetic field is introduced in the directionextending along the film plane direction of said lamination layer film,said bias magnetic field is applied in the direction intersectingsubstantially the direction in which said detection magnetic field isintroduced and in the direction extending along said film planedirection and that directions of magnetic fields substantially appliedto a front end and a rear end of the side in which said detectionmagnetic field is introduced are set to the same directions in said freelayer under the condition that said detection magnetic field is notapplied to said magneto-resistive effect element.
 7. A magnetic headusing magneto-resistive head according to claim 6, characterized in thatsaid magnetic fields substantially applied to the front end and the rearend of the side into which said detection magnetic field is introducedunder the condition that said detection magnetic field is not applied tosaid magneto-resistive effect element are increased in intensity in saidrear end side of said free layer.
 8. A magnetic head usingmagneto-resistive head according to claim 6, characterized in that saidmagnetic fields substantially applied to the front end and the rear endof the side into which said detection magnetic field is introduced underthe condition that said detection magnetic field is not applied to saidmagneto-resistive effect element are increased in intensity in saidfront end side of said free layer.
 9. A magnetic head usingmagneto-resistive head according to claim 6, 7 or 8, characterized inthat said magneto-resistive effect element body has a spin-valve typeconfiguration in which said spacer layer is comprised of a nonmagneticconductive layer.
 10. A magnetic head using magneto-resistive headaccording to claim 6, 7 or 8, characterized in that saidmagneto-resistive effect element body has a tunnel type configuration inwhich said spacer layer is comprised of a tunnel barrier layer.